From the time of the Liao dynasty (907–1125)it , Benxi was the centre of a small-scale iron industry, and coal began to be mined in the late 18th century. The startling dramatic modern growth of Pen-hsi the city began with the establishment in 1905 of the Pen-hsi Benxi (or Benxihu) Coal Mining Company with joint Chinese and Japanese capital. In 1911 the company began iron smelting and changed its name to the Pen-hsi Benxi Coal and Iron Company. It was efficiently managed and remained important, but it gradually became dominated by Japanese interests (its Japanese name was Honkei or Honkeiko).

After the establishment of the Japanese puppet state of Manchukuo (formerly Chinese ManchuriaManzhouguo) in Manchuria (present-day Northeast China) in 1932 and the formulation of the Manchurian Industrial Development Plan in 1936, the Manchukuo government developed Pen-hsi’s Benxi’s iron and steel production. Much of the iron from Pen-hsi Benxi had a low phosphorus and sulfur content and was in demand for the munitions industry. The city’s works also began to produce special steels for the Japanese navy. In 1945–46 the occupying Soviet forces April 1942 the mine was the site of one of the world’s worst coal-mining disasters, an explosion that killed hundreds of miners.

In 1945–46 the region was occupied by Soviet forces, who dismantled most of the equipment; however, but the plant was soon restoredby 1950, and during the early 1950s much new equipment was installed by Soviet technicians. By 1957 Pen-hsi’s Benxi’s iron production had reached the World War II level, and new local sources of ore were being exploited. The iron industry there is closely integrated with the large iron and steel complex at An-shanAnshan to the west, to which much of Pen-hsi’s Benxi’s pig iron production is transported. Since 1958 the steel output of Pen-hsi Benxi has been greatly increased. Pen-hsi also Benxi has large plants that manufacture cement, chemicalchemicals, and nonferrous alloy manufacturing industries. It also has thermal alloys; there are also thermal electric-power stations. It is connected by rail with Shen-yang, An-shan, and Lü-ta (Ta-lien)and expressway with Shenyang and Anshan and with the port city of Dalian to the southwest. Air pollution has become a serious problem for Benxi, as it is situated in a sheltered river valley and has a heavy industrial base. Pop. (2003 2002 est.) 834,176; (2007 est.) urban agglom., 1,012,000.